Method of handling call in handover in wireless communication system and wireless communication device using the same

ABSTRACT

A method of handling at least a call in handover in a wireless communication system and a communication device using the same are proposed. The wireless communication system includes at least a wireless communication network and a wireless communication device. The method includes the following steps. First, a wireless communication device receives a message for switching at least a packet-switched (PS) call to at least a circuit-switched (CS) call from the wireless communication network. Further, the wireless communication device sets a stream identifier of each of the CS calls to an identifier value. The method enables smooth single radio voice call continuity (SRVCC) handover from the PS call in one wireless communication network to the CS call in another wireless communication network. In addition, the method also enables SRVCC multicall handover from the PS call in one network operation mode to the CS call in another wireless communication network.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application of and claims the priority benefit ofU.S. patent application Ser. No. 12/776,436, filed on May 10, 2010, nowallowed, which claims priority benefit of U.S. provisional applicationSer. No. 61/180,138, filed on May 21, 2009. The entirety of theabove-mentioned patent applications is hereby incorporated by referenceherein and made a part of this specification.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a method of handling at least a call inhandover in a wireless communication system and a wireless communicationdevice using the same, and more particularly, to a method of handling atleast a packet-switched (PS) call handover to at least acircuit-switched (CS) call in different wireless communication networksand a wireless communication device using the same.

Description of Related Art

Currently, evolved Universal Telephone System Terrestrial Radio AccessNetwork (E-UTRAN) is designed to have only packet-switched (PS)connections, and voice call applications in the E-UTRAN have to beprovided in a form of voice over Internet Protocol (VoIP) application oran IP multimedia subsystem (IMS) voice call. However, most operatorsrunning the E-UTRAN may still have other types of networks based onother wireless communication technologies, and the operators would liketo have a seamless and smooth handover of the VoIP call or the IMS voicecall from the E-UTRAN to other networks. For example, one of theoperators running the E-UTRAN may have an UTRAN and a Global System forMobile communications (GSM) Enhanced data rate for GSM evolution radioaccess network (thereafter abbreviated as GERAN). When a user equipment(UE) with multicall capability has the IMS voice call under one of thePS domain connections in the E-UTRAN and the E-UTRAN initiates a singleradio voice call continuity (SRVCC) handover correspondingly, the UE maytransfer the IMS voice call to a CS call in either the UTRAN or theGERAN since the CS call has better quality of service (QoS) capabilitiessuch as low latency, low bit error rate, and low timing jitter.

It is currently not clear on whether the UE and the UTRAN (or the GERAN)sets the identical stream identifier (SI) for the CS call. Usually, theUE supporting multicall (i.e. having multicall capability) includes theSI in a SETUP message which is to be sent to the UTRAN or the GERAN. Thenetworks (e.g., the UTRAN or the GERAN) which support multicall mayinterpret the SI value after receiving the SETUP message from the UE asthe following. If the UE generates a new SI value at an initiation of anoriginating call, then a new traffic channel has to be assigned to theoriginating call. On the contrary, if the UE just indicates an existingSI value, then the indicated traffic channel has to be used for theoriginating call. The UE supporting multicall shall never send anadditional SETUP with indication that a new traffic channel is requestedto a wireless communication network that does not support multicall.

Moreover, if the UE supporting the multicall, the UE has to include theSI information element in the SETUP message. For the first call (i.e.,when there is no other ongoing call), the SI may initially start from 1.Usually the SI value may have three bits. However, if the UE does notset the SI value for the CS call but the network sets it to 1, later onwhen the UE initiates a CS streaming call and the UE sets the SI valueto 1 for the CS streaming call, it may cause the streaming CS call setupfailed since the UTRAN (or the GERAN) considers the SI=1 already beenset for one CS voice call. Beside, the UTRAN or the GERAN cannot use thetraffic channel configuration of the CS voice call for the CS streamingcall since radio access bearer (RAB) identifier or the traffic channelidentifier is required to be identical to the SI. In addition, it isalso currently not clear how to handle multicall in handover from theE-UTRAN to either the UTRAN or the GERAN.

Therefore, how to handle calls or multicall in handover in wirelesscommunication systems and related communication devices becomes animportant issue to be researched and discussed.

SUMMARY OF THE INVENTION

Accordingly, the present invention proposes a method of handling atleast a PS call handover to at least a CS call in different wirelesscommunication networks and a wireless communication device using thesame. The method enables a smooth single radio voice call continuity(SRVCC) handover from at least a PS call in one network operation modeto at least a CS call in another network operation mode. In addition,the method also enables a SRVCC multicall handover from at least a PScall in one wireless communication network to at least a CS call inanother wireless communication network.

The present invention proposes a method of handling at least a call inhandover in a wireless communication system. The wireless communicationsystem includes at least a wireless communication network and a wirelesscommunication device. The method includes the following steps. First,the wireless communication device receives a message for switching atleast a PS call to at least a CS call from the wireless communicationnetwork. Further, the wireless communication device sets a streamidentifier to at least the CS call to an identifier value.

The present invention also proposes the wireless communication devicefor handling at least a call in handover in the wireless communicationsystem. The wireless communication device includes a message receivingmodule, a stream identifier configuration module, a transceiver module,a memory module, and a processor. The message receiving module receivesa message for switching PS calls to CS calls from a wirelesscommunication network. Besides, the stream identifier configurationmodule sets a stream identifier of each of the CS calls to an identifiervalue. Further, the transceiver module transmits information to andreceives information from the wireless communication network, whereinthe information received includes the message for switching the PS callsto the CS calls from the wireless communication network. The memorymodule stores at least the message for switching the PS calls to the CScalls from the wireless communication network. In addition, theprocessor executes the message receiving module and the streamidentifier configuration module, and controls the transceiver module.

The present invention proposes a method of handling at least a call inhandover in a wireless communication system and a wireless communicationdevice for handling at least a call in handover in a wirelesscommunication system. The wireless communication device sets the streamidentifier of at least the CS call to the identifier value afterreceiving a message for switching at least the PS call in one operationmode to at least the CS call in another operation mode, wherein themessage is sent from the wireless communication network. The wirelesscommunication network also sets the stream identifier for at least theCS call to the identical identifier value. Therefore, the method mayavoid at least the CS call setup failure due to no agreement on thestream identifier for at least the CS call set by the wirelesscommunication device and the wireless communication network. Inaddition, the method also enables SRVCC multicall handover from at leastthe PS call in one wireless communication network to at least the CScall in another wireless communication network.

In order to make the features and advantages of the present inventioncomprehensible, exemplary embodiments accompanied with figures aredescribed in detail below.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, and are intended toprovide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a flow diagram illustrating an exemplary process of handlingat least a call in handover in a wireless communication system accordingto a first exemplary embodiment of the present invention.

FIG. 2 is a flow diagram illustrating an exemplary process of handlingat least a call in handover in a wireless communication system accordingto a second exemplary embodiment of the present invention.

FIG. 3 is a flow diagram illustrating an exemplary process of handlingat least a call in handover in a wireless communication system accordingto a third exemplary embodiment of the present invention.

FIG. 4 is a flow diagram illustrating an exemplary process of handlingat least a call in handover in a wireless communication system accordingto a fourth exemplary embodiment of the present invention.

FIG. 5 is a flow diagram illustrating an exemplary process of handlingat least a call in handover in a wireless communication system accordingto a fifth exemplary embodiment of the present invention.

FIG. 6 is a schematic block diagram illustrating a structure of awireless communication device for handling at least a call in handoverin a wireless communication system according to a sixth exemplaryembodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to the present embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers are used in thedrawings and the description to refer to the same or like parts.

The present invention proposes a method of handling call(s) in handoverin a wireless communication system. The wireless communication systemincludes at least a wireless communication network and a wirelesscommunication device. The method includes the following steps. First,the wireless communication device receives a message for switching thepacket-switched (PS) call(s) to the circuit-switched (CS) call(s) fromthe wireless communication network. Further, the wireless communicationdevice sets a stream identifier of each of the CS calls to an identifiervalue.

The present invention also proposes the wireless communication devicefor handling at least a call in handover in a wireless communicationsystem. The wireless communication device includes a message receivingmodule, a stream identifier configuration module, a transceiver module,a memory module, and a processor. The message receiving module receivesthe message for switching PS calls to CS calls from the wirelesscommunication network. Besides, the stream identifier configurationmodule sets the stream identifier of each of the CS calls to theidentifier value. Further, the transceiver module transmits informationto and receives information from the wireless communication network,wherein the information received includes the message for switching thePS calls to the CS calls from the wireless communication network. Thememory module stores at least the message for switching the PS calls tothe CS calls from the wireless communication network. In addition, theprocessor executes the message receiving module and the streamidentifier configuration module, and controls the transceiver module.

In all exemplary embodiments of the present invention, the wirelesscommunication system includes at least the wireless communicationnetwork and the wireless communication device. The wirelesscommunication network may include more than one operation modes, or mayinclude more than two sub-networks. For example, the wirelesscommunication network may include a Universal Mobile Telephone SystemTerrestrial Radio Access Network (UTRAN), an evolved UTRAN (E-UTRAN),and a Global System for Mobile communications (GSM) Enhanced data ratefor GSM evolution radio access network (thereafter abbreviated asGERAN). Similarly, the wireless communication device may also havecapability to transmit information to and receive information from theUTRAN, the E-UTRAN, and the GERAN. The above-described wirelesscommunication system is not intended to limit the present invention, andthe wireless communication system may include more than one wirelesscommunication network and more than one wireless communication device.

In a case of one exemplary embodiment of the present invention where thewireless communication network is integrated by different independentnetworks (e.g., the UTRAN, the E-UTRAN, and the GERAN), the wirelesscommunication device is capable of moving around in these independentnetworks but may have to handover the PS call or handover the PS callsestablished previously from one network (e.g., the E-UTRAN) to the CScalls in another sub-network (e.g., the UTRAN). Further, the wirelesscommunication device may have multicall capability, which means that:the wireless communication device supports simultaneously at least twoCS calls. In addition, it is to be noted that the PS calls may beadapted for single radio voice call continuity (SRVCC).

FIG. 1 is a flow diagram illustrating an exemplary process 100 ofhandling at least a call in handover in a wireless communication systemaccording to a first exemplary embodiment of the present invention.Referring to FIG. 1, in the first exemplary embodiment of the presentinvention, prior to process block S102, the wireless communicationdevice (for a purpose of simplicity, hereinafter referred as UE) isassumed to have multicall capability and has established at least the PScall in the wireless communication network. However, due to somereasons, the wireless communication network initiates a message forswitching at least a PS call from one network (e.g., the E-UTRAN) to atleast a CS call in another sub-network (e.g., the UTRAN). Some reasonsmentioned above, are such as network capacity limitations, poorsignal-to-noise ratio (SNR), poor signal strength level, and so on. Theprocess 100 starts at the process block S102. After the process blockS102, the process 100 may transit to process block S104.

At the process block S104, the UE receives the message for switching atleast a PS call to at least a CS call from the wireless communicationnetwork. It should be noted that the message for switching at least thePS call to at least the CS call from the wireless communication networkis a handover command. Besides, the handover command may be a handoverto UTRAN command, and a radio access bearer (RAB) identifier of a CS RABis included in the handover to UTRAN command for the CS call. Further,the handover command may be a handover to GERAN command, and a RABidentifier of the CS RAB is included in the handover to GERAN commandfor the CS call. After the process block S104, the process 100 maytransit to process block S106.

At the process block S106, the UE sets a stream identifier of at leastthe CS call to an identifier value. Correspondingly, the wirelesscommunication network sets the stream identifier, stored at the wirelesscommunication network, of at least the CS call to the identicalidentifier value as set by the UE. It is noted that, in the followingexemplary embodiments, the identifier value is the radio access bearer(RAB) identifier of a CS RAB included in the handover to UTRAN commandfor the CS call, the radio access bearer (RAB) identifier of a CS RABincluded in the handover to GERAN command for at least the CS call, or adefault value. The default value may be equal to 1, but the value of thedefault value is not used to limit the present invention.

After the process block S106, the process 100 may transit to processblock S108. At the process block S108, the process 100 terminates.Furthermore, when at least the PS call comprises a plurality of PScalls, and at least the CS call comprises a plurality of CS calls, theUE sets stream identifiers of the CS calls to identifier valuesrespectively at the process block S106. Correspondingly, the wirelesscommunication network sets the stream identifiers, stored at thewireless communication network, of the CS calls to the identicalidentifier values as set by the UE.

Alternatively, the process 100 may be repeated periodically, in acontinuous fashion, or upon being triggered as a result of a condition,such as a poor SNR situation detected by the UE. In addition, theprocess blocks S102-S108 may be repeated periodically, in a continuousfashion, or upon being triggered as a result of a condition, withoutrepeating the entire process 100. For example, the process blocksS102-S108 may be repeated a number of times in response to impetuses inwhich the poor SNR situation is detected by the UE. Other combinationsand permutations are possible as well.

FIG. 2 is a flow diagram illustrating an exemplary process 200 ofhandling at least a call in handover in a wireless communication systemaccording to a second exemplary embodiment of the present invention.Referring to FIG. 2, in the second exemplary embodiment of the presentinvention, the UE has established at least a PS call, such as an IPmultimedia subsystem (IMS) call, in the wireless communication networkprior to process block S202. The IMS call, for example, may be aninstant message, a video call, a voice call, any other session initialprotocol (SIP) based calls, or any other Session Initiation Protocolbased (SIP-based) communication applications. In particular, the voicecall of the IMS call may be a voice over Internet protocol (VoIP) call.In addition, the process 200 is similar to the process 100 of FIG. 1,and the process blocks S204-S214 are described herein below.

At the process block S204, the UE receives the message for switching atleast a PS call to at least a CS call from the wireless communicationnetwork. The message for switching at least the PS call to at least theCS call from the wireless communication network is the handover commandand includes the identifier value and the radio link configuration forat least the CS call. When the wireless communication device currentlyhas more than one PS calls to be switched to the CS calls, the messagefor switching the PS calls to the CS calls from the wirelesscommunication network is the handover command and includes theidentifier values and the radio link configurations respectively for theCS calls. Besides, the handover command may be the handover to UTRANcommand, and the identifier value is the RAB identifier of the CS RABincluded in the handover to UTRAN command for the CS call. Further, thehandover command may be the handover to GERAN command, and theidentifier value is the RAB identifier of the CS RAB included in thehandover to GERAN command for the CS call. After the process block S204,the process 200 may transit to process block S206.

At the process block S206, the UE sets a stream identifier of at leastthe CS call to an identifier value. Correspondingly, the wirelesscommunication network sets the stream identifier, stored at the wirelesscommunication network, of at least the CS call to the identicalidentifier value as set by the UE. It is noted that, the identifiervalue is the radio access bearer (RAB) identifier of a CS RAB includedin the handover to UTRAN command for the CS call, or the radio accessbearer (RAB) identifier of a CS RAB included in the handover to GERANcommand for at least the CS call.

After process block S206, the process 200 may transit to process blockS208. At the process block S208, the UE determines if there is currentlymore than one PS calls to be switched to CS calls. If yes, then afterthe process block S208, the process 200 may transit to process blockS210. If no, then after the process block S208, the process 200 maytransit to process block S212.

At the process block S210, the UE maps a radio link configuration ofeach of the CS calls to an application which handles a corresponding IMScall according to CS radio access bearer (RAB) attributes. Theapplication handling the IMS call, for example, may be an instantmessage application, a video call application, a voice call application,or any other SIP-based communication applications. In particular, theapplication handling the IMS call may be a VoIP call application.Besides, the message for switching the PS calls to the CS calls from thewireless communication network includes the identifier value and theradio link configuration for each of the CS calls. The UE may furtherdetermine a type of the application handling the corresponding IMS callaccording to radio link configuration of the PS calls. For example, ifthe data rate included in the radio link configuration is high, theapplication handling the corresponding IMS call may be determined as thestreaming application. On the other hand, if the data rate included inthe radio link configuration is low, the application handling thecorresponding IMS call may be determined as the voice call applicationor the VoIP call application. Moreover, it should be noted that if thehandover command is determined as the handover to GERAN command in theprocess block S204, then there is only one PS call to be switched to theCS call, and usually the PS call with a preset highest priority isswitched to the CS call while the remaining PS calls (if they exist)would be discarded or handover to PS domains. Further, in such a case,the UE just maps a radio link configuration of the CS call to theapplication which handles a corresponding IMS call according to CS radioaccess bearer (RAB) attributes.

In the other exemplary embodiment, another manner to map a radio linkconfiguration of each of the CS calls to an application which handles acorresponding IMS call according to CS radio access bearer (RAB)attributes in the process block S110 is illustrated below. The UEdetermines a CS RAB is a voice call or a data call according to a CS RABconfiguration. Based upon the foregoing example, the UE may determinewhether the CS RAB is a CS adaptive multi-rate (AMR) narrowband (NB)voice call or a CS AMR wideband (WB) voice call according to a data rateof the CS RAB. For another example, the UE may also determine whetherthe CS RAB is the CS AMR NB voice call or a CS AMR WB voice callaccording to a number of radio bearers (RBs) included in the CS RAB whenthe CS RAB is determined for a voice call. For example, if one of the CSRAB includes three RBs, then the CS RAB may be determined as for the CSAMR NB voice call. For another example, if another CS RAB includes twoRBs, then the CS RAB may be determined as for the CS AMR WB voice call.However, the present invention is not limited to the above-describedexamples, other exemplary embodiments of the present invention maydetermine whether the CS RAB is the CS AMR NB voice call or a CS AMR WBvoice call according to other parameters. Further, the UE may alsodetermine the CS RAB is for a data call if the number of RB included inthe CS RAB is 1. Moreover, the UE determines the data rate of the CS RABaccording to the CS RAB configuration. If the handover command isdetermined as the handover to GERAN command in the process block S204,the UE determines whether the CS RAB is a CS full rate (FR) voice call,a CS half rate (HR) voice call, a CS enhanced full rate (EFR) voicecall, or a CS AMR NB voice call according the data rate of the CS RAB.After the process block S210, the process 200 may transit to processblock S212. At the process block S212, the process 200 terminates.Alternatively, the process 200 may be repeated periodically, in acontinuous fashion, or upon being triggered as a result of a condition,such as the poor SNR situation detected by the UE.

In addition, the process blocks S202-S212 may be repeated periodically,in a continuous fashion, or upon being triggered as a result of acondition, without repeating the entire process 200. For example, theprocess blocks S202-S212 may be repeated a number of times in responseto impetuses in which the poor SNR situation is detected by the UE.Other combinations and permutations are possible as well.

FIG. 3 is a flow diagram illustrating an exemplary process 300 ofhandling at least a call in handover in a wireless communication systemaccording to a third exemplary embodiment of the present invention.Referring to FIG. 3, in the third exemplary embodiment of the presentinvention, the process 300 is similar to the process 100 of FIG. 1, andthe process blocks S304 and S306 are described below. The process 300starts from the process block S302 and then transit to process blockS304.

At the process block S304, the UE receives the message for switching atleast a PS call, such as an IMS call, to at least a CS call from thewireless communication network. It should be noted that the message forswitching at least the PS call to at least the CS call from the wirelesscommunication network is a handover command. Besides, the handovercommand may be a handover to UTRAN command, and a radio access bearer(RAB) identifier of a CS RAB is included in the handover to UTRANcommand for the CS call. Further, the handover command may be a handoverto GERAN command, and a RAB identifier of the CS RAB is included in thehandover to GERAN command for the CS call.

After process block S304, the process 300 may transit to process blockS306. At the process block S306, the UE sets the stream identifier of atleast the CS call to a default value. In other words, in the thirdexemplary embodiment of the present invention, the identifier value isthe default value. Besides, the default value is 1 in the thirdexemplary embodiment of the present invention. However, the presentinvention is not limited to the above-described example; other exemplaryembodiments of the present invention may set the default value to afigure other than 1. After the process block S306, the process 300 maytransit to process block S308. At the process block S308, the process300 terminates. Alternatively, the process 300 may be repeatedperiodically, in a continuous fashion, or upon being triggered as aresult of a condition, such as the poor SNR situation detected by theUE.

In addition, the process blocks S302-S308 may be repeated periodically,in continuous fashion, or upon being triggered as a result of acondition, without repeating the entire process 300. For example, theprocess blocks S302-S308 may be repeated a number of times in responseto impetuses in which the poor SNR situation is detected by the UE.Other combinations and permutations are possible as well.

FIG. 4 is a flow diagram illustrating an exemplary process 400 ofhandling at least a call in handover n a wireless communication systemaccording to a fourth exemplary embodiment of the present invention.Referring to FIG. 4, in the fourth exemplary embodiment of the presentinvention, the process 400 is similar to the process 100 of FIG. 1, andthe process 400 is described below. The process 400 starts from theprocess block S402, and then transits to process block S404.

At the process block S404, the UE receives the message for switching atleast a PS call to at least a CS call from the wireless communicationnetwork. It should be noted that the message for switching at least thePS call to at least the CS call from the wireless communication networkis a handover command. Besides, the handover command may be a handoverto UTRAN command, and a radio access bearer (RAB) identifier of a CS RABis included in the handover to UTRAN command for the CS call. Further,the handover command may be a handover to GERAN command, and a RABidentifier of the CS RAB is included in the handover to GERAN commandfor the CS call.

After process block S404, the process 400 may transit to process blockS406. At the process block S406, the UE disables the multicallcapability. Since the multicall capability is disabled in the fourthexemplary embodiment, if there are more than one PS calls to be switchedto the CS calls, then just one of the PS calls is switched to the CScall. Usually the PS call with a preset highest priority is switched tothe CS call while the remaining PS calls (if they exist) would bediscarded. After the process block S406, the process 400 may transit toprocess block S410.

After the process block S406, the process 400 may transit to processblock S410. At the process block S410, the UE enables the multicallcapability when the CS call is released. After the process block S410,the process may transit to the process block S412. At the process blockS412, the process 400 terminates. Alternatively, the process 400 may berepeated periodically, in a continuous fashion, or upon being triggeredas a result of a condition, such as the poor SNR situation detected bythe UE.

In addition, the process blocks S402-S412 may be repeated periodically,in a continuous fashion, or upon being triggered as a result of acondition, without repeating the entire process 400. For example, theprocess blocks S402-S412 may be repeated a number of times in responseto impetuses in which the poor SNR situation is detected by the UE.Other combinations and permutations are possible as well.

FIG. 5 is a flow diagram illustrating an exemplary process 500 ofhandling at least a call in handover in a wireless communication systemaccording to a fifth exemplary embodiment of the present invention.Referring to FIG. 5, in the fifth exemplary embodiment of the presentinvention, the process 500 is similar to the process 100 of FIG. 1 andthe process 400 of FIG. 4, and the process 500 is described below. Theprocess 500 starts from the process block S502, and then transits toprocess block S504.

At the process block S504, the wireless communication network considersif the UE supports multicall and determines the number of PS calls to beswitched to CS calls. Assuming the wireless communication network is notaware of whether the UE has the multicall capability prior to theprocess 500 starts, so the wireless communication network firstdetermines if the UE has the multicall capability. After the processblock S506, the process 500 may transit to process block S506.

At the process block S504, the UE receives the message for switching atleast a PS call to at least a CS call from the wireless communicationnetwork. It should be noted that the message for switching at least thePS call to at least the CS call from the wireless communication networkis a handover command. Besides, the handover command may be a handoverto UTRAN command, and a radio access bearer (RAB) identifier of a CS RABis included in the handover to UTRAN command for the CS call. Further,the handover command may be a handover to GERAN command, and a RABidentifier of the CS RAB is included in the handover to GERAN commandfor the CS call. At least the PS call and at least the CS call may beone PS call and one CS call, when the network determines the UE does nothave multicall capability. By contrast, at least the PS call and atleast the CS call may comprise PS calls and CS calls respectively, whenthe network determines the UE has the multicall capability and one morethan PS calls are to be switched to more than one CS calls.

At the process block S508, if the UE is determined to have the multicallcapability, the UE sets the stream identifier of at least the CS callsto the identifier value. Correspondingly, the wireless communicationnetwork sets the stream identifier, stored at the wireless communicationnetwork, of at least the CS call to the identical identifier value asset by the UE. On the contrary, if the UE is determined to have nomulticall capability, the UE switches just one of the PS calls to the CScall when the UE does not support multicall. Usually the PS call withthe preset highest priority is switched to the PS call while theremaining PS calls (if they exist) would be discarded or handover to PSdomains. After the process block S508, the process 500 may transit toprocess block S510. At the process block S510, the process 500terminates. Alternatively, the process 500 may be repeated periodically,in a continuous fashion, or upon being triggered as a result of acondition, such as the poor SNR situation detected by the UE.

In addition, the process blocks S502-S510 may be repeated periodically,in a continuous fashion, or upon being triggered as a result of acondition, without repeating the entire process 500. For example, theprocess blocks S502-S510 may be repeated a number of times in responseto impetuses in which the poor SNR situation is detected by the UE.Other combinations and permutations are possible as well.

The present invention also proposes a wireless communication deviceusing the method of handling at least a call in handover in a wirelesscommunication system. The wireless communication device is described indetails below.

FIG. 6 is a schematic block diagram illustrating a structure of awireless to communication device 600 for handling at least a call inhandover in a wireless communication system according to a sixthexemplary embodiment of the present invention. Referring to FIG. 6, thewireless communication device 600 includes a message receiver module610, a stream identifier configuration module 620, a transceiver module630, a PS call number determination module 640, a radio linkconfiguration mapping module 650, a CS RAB determination module 660, amulticall capability disabler module 670, a multicall capability enablermodule 675, and a PS call-CS call switcher module 680, a processor 690,and a memory module 695.

The message receiver module 610 receives the message for switching atleast a PS call to at least a CS call from the wireless communicationnetwork. Besides, the stream identifier configuration module 620 setsthe stream identifier of at least the CS call to the identifier value.Moreover, the transceiver module 630 transmits the information to andreceives the information from the wireless communication network,wherein the information received includes the message for switching atleast the PS call to at least the CS call from the wirelesscommunication network.

The PS call number determination module 640 determines whether thewireless communication device currently has more than one PS calls to beswitched to the CS calls. Besides, the radio link configuration mappingmodule 650 maps the radio link configuration of each of the CS call tothe application handling corresponding the IMS call according to the CSRAB attributes if the wireless communication device is determined ascurrently having more than one PS calls to be switched to the CS calls.

The CS RAB determination module 660 determines whether the CS RAB is forthe voice call or for the data call according to the CS RABconfiguration.

The multicall capability disabler module 670 disables the multicallcapability of the wireless communication device. On the contrary, themulticall capability enabler module 675 enables the multicall capabilityof the wireless communication device when the wireless communicationdevice releases the CS call.

The PS call-CS call switcher module 680 switches at least the PS call toat least the CS call. More specifically, the PS call-CS call switchermodule 680 switches at least the PS call originally in one network (e.g,the E-UTRAN) to at least the CS call in another network (e.g., the UTRANand the GERAN).

The memory module 695 stores software programs or software modulesrelated to the message receiver module 610, the stream identifierconfiguration module 620, the transceiver module 630, the PS call numberdetermination module 640, the radio link configuration mapping module650, the CS RAB determination module 660, the multicall capabilitydisabler module 670, the multicall capability enabler module 675, andthe PS call-CS call switcher module 680 and at least the message forswitching at least the PS call to at least the CS call from the wirelesscommunication network. Besides, the memory module 695 may be one or morememory devices, adapted for storing data and software programs. Forexample, the memory module 695 may be a RAM, a ROM, a magnetic storagedevice, a flash memory storage device, or an optical storage device.

The processor 690 executes the message receiver module 610, the streamidentifier configuration module 620, the PS call number determinationmodule 640, the radio link configuration mapping module 650, the CS RABdetermination module 660, the multicall capability disabler module 670,the multicall capability enabler module 675, and the PS call-CS callswitcher module 680 and controlling the transceiver module 630. Inaddition, the processor 690 may execute other software applications orsoftware modules stored on the memory module 695.

The wireless communication device 600 may transmit information to andreceive information from the wireless communication network (e.g., theE-UTRAN, the UTRAN, and the GERAN) and may apply any of theabove-described exemplary processes for handling at least a call inhandover in the wireless communication system according to the exemplaryembodiments mentioned previously.

The above-described exemplary embodiments of the present invention mayalso be embodied as computer-readable codes on a computer-readablerecording medium. The computer-readable recording medium is any datastorage device that may store data, which may thereafter be read by acomputer system. Examples of the computer-readable recording mediuminclude, but are not limited to, Read-Only Memory (ROM), Random-AccessMemory (RAM), CD-ROMs, magnetic tapes, floppy disks, flash memory,optical data storage devices, and carrier waves (such as datatransmission through the Internet via wired or wireless transmissionpaths). The computer-readable recording medium may also be distributedover network-coupled computer systems so that the computer-readable codeis stored and executed in a distributed fashion. Also, functionprograms, codes, and code segments for accomplishing the presentinvention may be easily construed as within the scope of the inventionby programmers skilled in the art to which the present inventionpertains.

In summary, the embodiments of the present invention proposes the methodof handling at least a call in handover in the wireless communicationsystems and the wireless communication device for handling at least acall in handover in a wireless communication system. The wirelesscommunication device sets the stream identifier of at least the CS callto the identifier value after receiving the message for switching atleast a PS call in one wireless communication network to at least a CScall in another wireless communication network, wherein the message issent from the wireless communication network. The wireless communicationnetwork may also set the stream identifier for at least the CS call tothe identical identifier value correspondingly. Therefore, the methodmay avoid at least the CS call setup failure due to no agreement on thestream identifier for at least the CS call. In addition, the method alsoenables SRVCC multicall handover from at least the PS call in onewireless communication network to at least the CS call in anotherwireless communication network.

Although the present invention has been disclosed above by the exemplaryembodiments, they are not intended to limit the present invention.Anybody skilled in the art can make some modifications and variationswithout departing from the spirit and scope of the present invention.Therefore, the protecting range of the present invention falls in theappended claims.

What is claimed is:
 1. A method of handling at least a call in handoverin a wireless communication system, wherein the wireless communicationsystem comprising at least a wireless communication network and awireless communication device, the method comprising: receiving amessage at the wireless communication device from the wirelesscommunication network which transmits the message to initiate a singleradio voice call continuity (SRVCC) handover for switching at least apacket-switched (PS) call to at least a CS call, wherein the wirelesscommunication device is a user equipment (UE) with multicall capabilityof supporting simultaneously at least two circuit-switched (CS) calls;and disabling, at the wireless communication device, the multicallcapability in response to receiving the message for initiating the SRVCChandover, to switch one of the at least a PS call with a preset highestpriority to the CS call and discard the other of the at least a PS call.2. The method claimed in claim 1, further comprising: setting, at thewireless communication device, a stream identifier of the CS call to anidentifier value in response to receiving the message for initiating theSRVCC handover.
 3. The method as claimed in claim 2, wherein theidentifier value is a default value.
 4. The method as claimed in claim2, wherein the wireless communication network further sets a streamidentifier of the CS call to the identifier value in response totransmitting the message for initiating the SRVCC handover.
 5. Themethod as claimed in claim 2, wherein the message is a handover toUniversal Mobile Telephone System Terrestrial Radio Access Network(UTRAN) command, and the identifier value is a radio access bearer (RAB)identifier of a CS RAB included in the handover to UTRAN command for theCS call.
 6. The method as claimed in claim 5, wherein the wirelesscommunication device determines whether the CS RAB is for a CS adaptivemulti-rate (AMR) narrowband (NB) voice call or for a CS AMR wideband(WB) voice call according to a number of radio bearers (RBs) included inthe CS RAB when the CS RAB is determined for a voice call.
 7. The methodas claimed in claim 2, wherein the message is a handover to GSM EDGERadio Access Network (GERAN) command, and the identifier value is a RABidentifier of a CS RAB included in the handover to GERAN command for theCS call.
 8. The method as claimed in claim 7, wherein the wirelesscommunication device further determines whether the CS RAB is for a CSfull rate (FR) voice call, for a CS half rate (HR) voice call, for a CSenhanced full rate (EFR) voice call, or for a CS AMR adaptive multi-rate(AMR) narrowband (NB) voice call according to a data rate of the CS RAB.9. The method as claimed in claim 1, further comprising: enabling, atthe wireless communication device, the multicall capability when thewireless communication device releases the CS call.
 10. A wirelesscommunication device, the wireless communication device comprising: amessage receiver, configured for receiving a message from a wirelesscommunication network which transmits the message to initiate a singleradio voice call continuity (SRVCC) handover for switching at least apacket-switched (PS) call to at least a CS call, wherein the wirelesscommunication device is a user equipment (UE) with multicall capabilityof supporting simultaneously at least two circuit-switched (CS) calls;and a multicall capability disabler, configured for disabling themulticall capability in response to receiving the message for initiatingthe SRVCC handover to switch one of the at least a PS call with a presethighest priority to the CS call, and discarding the other of the atleast a PS call.
 11. The wireless communication device claimed in claim10, further comprising: a stream identifier configuration module,configured for setting a stream identifier of the CS call to anidentifier value in response to receiving the message for initiating theSRVCC handover.
 12. The wireless communication device as claimed inclaim 11, wherein the wireless communication network further sets astream identifier of the CS call to the identifier value in response totransmitting the message for initiating the SRVCC handover.
 13. Thewireless communication device as claimed in claim 11, wherein themessage is a handover to Universal Mobile Telephone System TerrestrialRadio Access Network (UTRAN) command, and the identifier value is aradio access bearer (RAB) identifier of a CS RAB included in thehandover to UTRAN command for the CS call.
 14. The wirelesscommunication device as claimed in claim 13, wherein the wirelesscommunication device determines whether the CS RAB is for a CS adaptivemulti-rate (AMR) narrowband (NB) voice call or for a CS AMR wideband(WB) voice call according to a number of radio bearers (RBs) included inthe CS RAB when the CS RAB is determined for a voice call.
 15. Thewireless communication device as claimed in claim 11, wherein themessage is a handover to GSM EDGE Radio Access Network (GERAN) command,and the identifier value is a RAB identifier of a CS RAB included in thehandover to GERAN command for the CS call.
 16. The wirelesscommunication device as claimed in claim 15, wherein the wirelesscommunication device further determines whether the CS RAB is for a CSfull rate (FR) voice call, for a CS half rate (HR) voice call, for a CSenhanced full rate (EFR) voice call, or for a CS AMR adaptive multi-rate(AMR) narrowband (NB) voice call according to a data rate of the CS RAB.17. The wireless communication device as claimed in claim 10, furthercomprising: a multicall capability enabler, configured for enabling themulticall capability when the wireless communication device releases theCS call.
 18. A method of handling at least a call in handover in awireless communication system, wherein the wireless communication systemcomprises at least a wireless communication network a wirelesscommunication device, the method comprising: receiving a message at thewireless communication device from the wireless communication networkwhich transmits the message to initiate a single radio voice callcontinuity (SRVCC) handover for switching at least a packet-switched(PS) call to at least a circuit-switched (CS) call, wherein the wirelesscommunication device is a user equipment (UE) having a multicallcapability and is capable of supporting at least two circuit-switched(CS) calls; disabling, at the wireless communication device, themulticall capability, to switch one of the at least a PS call with apreset highest priority to the CS call and discard the other of the atleast a PS call; and enabling, at the wireless communication device, themulticall capability when the wireless communication device releases theCS call.
 19. The method as claimed in claim 18, further comprising:setting, by the wireless communication device, a UE stream identifier ofthe CS call to an identifier value in response to receiving the messagefor initiating the SRVCC handover.
 20. The method as claimed in claim18, further comprising: setting, by the wireless communication network,a network stream identifier of the CS call to the identifier value inresponse to transmitting the message for initiating the SRVCC handover.